Southerners approach politeness in an almost British fashion. Almost, because there is a bit more emotion and effusiveness that the British seem to fear and recoil from. It is a way of talking around a subject, that Southerners parse fair quickly. Like the use of "God bless his poor, dear, sweet heart" is Southern for "my God but that boy is an idiot..." Though, when applied to a direct conversation, "bless your heart" generally translates to "I'm glad that such a mess of crap landed in your lap, and you deserve every moment of discomfort you mean spirited dumbass, and don't you dare track this mess back on me."

Or "I reckon you oughta" which means "do this now. Do it fast. Do it without question. Do this and drive your enemies before you and hear the lamentations of their women!"

"I like what you've done with your hair" generally translates to "Jeebus Frist what in the Hells did you let Trudy do to you, and have you no mirror?"

"I'll never tell a soul" usually means "O Lord, EVERYONE I know is going to hear about this." Add a "cross my heart" and it means that said person will tell all their friends to spread this around. "hope to die" adds on the implied meaning that family, friends and relations in distant states will know before your ass leaves the driveway.

Where the English deadpan and impassive, Southerners go warmer, effusive, and cattily b*tchy right to your face, saying the worst things in the world, in the very nicest of ways.